I've been doing a language exchange with some Japanese people every week - just talking in japanese and english and having a kinda relaxed lesson. They also got me some manga which has been really helpful. I'd been reading Japanese for Busy People and it's all -masu and these manga are a whole new world of language - they're teaching me a lot and they're a lot less stale than the Japanese for Busy People books. However, those books are great for explaining grammar and introducing different sentence structures. I think the best thing to do is - a mix of all of these things - read manga for slang/less formal way of saying things + new vocab, read textbook for practising grammar and sentence structures, listen to J-music/watch anime to relax and you'll notice yourself picking up what they're saying. Also it's great to find a japanese person to talk to. There are a ton on various websites looking for 'skype lessons'.
As for kanji, i've been working my way through the JLPT grade lists. I work in groups of about 10 - write down the kanji character, then it's meaning, then it's reading in hiragana, then i might start by writing all of the meanings in a different order and see if i can remember the kanji and the reading, then all of the readings and see if i can remember the kanji and the meaning. Then i hone in on the kanji i can't remember and write them over and over continuing to jumble up the meanings/character/reading to test myself.
good luck! : )